This proposal requests support for the purchase of a Leica TCS SP2 AOBS Vis-UV Confocal Microscope. This microscope, which will be a shared resource, will be crucial for the ongoing research of investigators working in several departments at the Stanford University School of Medicine. The projects of the major users investigate a range of NIH supported topics, including: i) cell polarity and asymmetric cell division in bacteria (Shapiro), epithelial cells (Nelson) and stem cells (Fuller), ii) intercellular signaling and cell fate in bacteria (Kaiser), mouse embryonic and neural stem cells (Nusse), and gametogenesis (Tazuke), iii) mechanisms of localized intracellular signaling by small molecule second messengers (Conti), iv) transcriptional regulation of neuronal and cardiovascular development (Crabtree), v) mechanisms of cytoskeletal function and membrane trafficking during cell division (Fuller), and vi) mechanisms of chromosome pairing and synapsis during meiosis (Villeneuve). All of these projects require precise localization of proteins or other cellular components in cultured cells or complex tissues. The ability to precisely localize proteins to specific cellular compartments and to infer protein interactions by colocalization provided by the requested shared Laser Scanning Confocal microscope will be crucial to elucidating the normal and pathogenetic mechanisms that regulate and mediate the important developmental and cellular events under investigation. The above projects are being undertaken by senior, intermediate, and recently recruited faculty members, who will cooperate in supporting this confocal facility. The enhanced resolution and sensitivity of this microscope, as well as its ability to effectively image several different fluors simultaneously in both single cells and in thicker tissue, will be crucial to the success of these NIH funded projects.